People are generally aware of the most common causes of hallucinations, like schizophrenia and a really high fever. But lesser known are the more rare causes; here are six you probably haven't heard about.

Math-inclined students always stood out from the reading-inclined students in the classroom, but after taking a closer look at the DNA, it turns out many of the genes that affect children’s reading skills also affect their math abilities. A new study from the University of Oxford and King’s College London published in the journal of Nature Communications indicates the literacy skills and mathematical abilities of 12-year-olds share about half of the same genes.

"We looked at this question in two ways, by comparing the similarity of thousands of twins, and by measuring millions of tiny differences in their DNA. Both analyses show that similar collections of subtle DNA differences are important for reading and maths. However, it's also clear just how important our life experience is in making us better at one or the other. It's this complex interplay of nature and nurture as we grow up that shapes who we are," said co-author Dr. Oliver Davis from UCL Genetics in a press release.

Researchers tested reading comprehension and fluency, along with mathematical questions on 12-year-old twins and another group of unrelated children from nearly 2,800 British families. When they compared the twins’ DNA sets with the results of their reading and math tests, they found thousands of subtle genetic changes that help shape a child’s performance in both subjects.

"This is the first time we estimate genetic influence on learning ability using DNA alone. The study does not point to specific genes linked to literacy or numeracy, but rather suggests that genetic influence on complex traits, like learning abilities, and common disorders, like learning disabilities, is caused by many genes of very small effect size,” said lead researcher of the TEDS study Robert Plomin professor of King's College London.

Previous twin studies confirm the genetic differences for children account for how easily it is for them to learn or perform math problems. Math and reading abilities are thought to have a complex system of genes that are developed both by nature and nurture influences. Mathematical and reading abilities are known to run in families, which means if your mom is a good reader, the likelihood of you becoming one increases. However, how much of this genetic link plays a role in your reading skills? What if Mom just read more to you because she had well-practiced reading skills?

"We're moving into a world where analyzing millions of DNA changes, in thousands of individuals, is a routine tool in helping scientists to understand aspects of human biology. This study used the technique to help investigate the overlap in the genetic component of reading and math ability in children,” said co-author Dr. Chris Spencer from Oxford University. “Interestingly, the same method can be applied to pretty much any human trait, for example to identify new links between diseases and disorders, or the way in which people respond to treatments."

Currently researchers have only recognized the gene variations but aren’t exactly sure what each variant does and how it affects brain development and function. By taking the step to understand the genetic relationship between reading and math skills, further research could help explain the influences of learning disabilities such as dyslexia and dyscalculia.

Dyslexia is a neurological and often genetic learning disability that makes word recognition, decoding, and spelling difficult, which is why it can cause problems with reading comprehension and slow vocabulary growth, according to the National Center for Learning Disabilities. Dyscalculia, on the other hand, is a learning disability that makes it difficult for a person to visually process problems, which hurts their math skills greatly.

“Children differ genetically in how easy or difficult they find learning, and we need to recognize, and respect, these individual differences. Finding such strong genetic influence does not mean that there is nothing we can do if a child finds learning difficult — heritability does not imply that anything is set in stone – it just means it may take more effort from parents, schools and teachers to bring the child up to speed,” Plomin said.